Preparation method of water-soluble amorphous iron oxide hollow nanospheres

Abstract

The invention discloses a preparation method of water-soluble amorphous iron oxide hollow nanospheres, which comprises the following specific steps: mixing soluble iron salt, ascorbic acid, hexadecyl trimethyl ammonium bromide and hexamethylenetetramine, dissolving in water, and uniformly stirring and mixing at room temperature to obtain a reaction solution A; heating the reaction liquid A to 80-120 DEG C, and stirring, refluxing and reacting for 1-12 hours to obtain a reaction liquid B; and precipitating and centrifuging the reaction liquid B by using excessive ethanol, washing for multiple times, and dispersing in water to obtain the water-soluble amorphous iron oxide hollow nanospheres. The iron oxide nanosphere prepared by the method is water-soluble and amorphous, has a hollow structure, has the size of about 40-100nm, has more active sites due to the nano size, larger specific surface area and the hollow structure, and can be further used for preparing a targeted drug carrier or a functional catalytic material carrier.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of iron oxide nanomaterials, and particularly relates to a method for preparing water-soluble amorphous iron oxide hollow nanospheres. Background Art

[0002] Porous nanomaterials have more active sites due to their nanosize and large specific surface area. They are a very important type of material in the field of nanocatalysis, and porous structures with drug loading capacity play an important role in the biomedical field. Therefore, the synthesis of nanomaterials with porous structures has very important practical significance and research prospects. Among them, iron oxide nanomaterials have attracted the attention of many researchers due to their excellent catalytic performance, magnetic resonance imaging and biocompatibility. There are many methods for the synthesis of iron oxide nanoparticles, including high-temperature solvothermal method, hydrothermal method, etc., but the synthesis of porous iron oxide nanoparticles is relatively rare.

[0003] The American Journal of Bioconjugate Chemistry (2018, Vol. 29, pp. 1283-1290) reported the synthesis of porous iron oxide nanoparticles with a size of ~200 nm. It used ferric chloride, sodium citrate, urea and polyacrylamide dissolved in water and then placed in a reactor at 200°C for 12 hours, and then washed to obtain porous iron oxide nanoparticles. The porous iron oxide nanoparticles prepared are too large and polycrystalline, and require the use of a high-temperature reactor, which has certain safety risks. Therefore, it is not conducive to the promotion of actual production.

[0004] Patent document CN105883932B discloses a method for preparing iron oxide nanospheres, which first prepares a precursor solution by mixing ferric nitrate nonahydrate, tetramethylammonium hydroxide and water, and then places the precursor solution in a reactor for hydrothermal reaction at 180-200°C for 9-10 hours, and obtains iron oxide nanospheres after filtering, washing and drying. Although the iron oxide nanospheres prepared by this patented technology are uniform in size and have a size of 65-75nm, the synthesis process still requires the use of a high-temperature reactor, which has certain safety risks, and the synthesized iron oxide nanospheres do not have a hollow structure.

[0005] The patent document of CN102659187A discloses a method for preparing water-soluble iron oxide nanoparticles, wherein ferric acetylacetonate and a modifier are dissolved in an organic solvent, and a transparent solution is prepared after stirring; the solution is then placed in a stainless steel reactor and heated to 120-240°C for 0.5-48 hours and then cooled; the reaction solution is centrifuged and dried to obtain monodisperse granular iron oxide nanoparticles with an average particle size of 5-50 nm, the modifier is polyvinyl pyrrolidone or polyethyleneimine, and the organic solvent is polyethylene glycol or triethylene glycol. The iron oxide nanoparticles prepared by this patented technology are monodisperse and water-soluble, but the synthesis process still requires the use of a high-temperature reactor, which has certain safety risks, and the synthesized iron oxide nanospheres do not have a hollow structure.

[0006] In summary, the existing synthesis methods of iron oxide nanoparticles either produce oil-soluble nanoparticles that require further water-soluble surface modification, which is cumbersome and increases costs; or they do not have a hollow structure; or they are too large and difficult to control; or the synthesis process requires the use of a high-temperature reactor, which increases safety risks and is not conducive to the promotion of actual production. Summary of the invention

[0007] The present invention aims to solve the technical problems in the prior art that the synthesis steps of iron oxide nanoparticles are complicated, the cost is high, there is no hollow structure, the size is too large, the synthesis process requires the use of a high-temperature reactor, which increases the safety risk and is not conducive to actual production and promotion. A method for preparing water-soluble amorphous iron oxide hollow nanospheres with simple process, low cost and easy operation is provided.

[0008] The present invention adopts the following technical solution to solve the above technical problems, a method for preparing water-soluble amorphous iron oxide hollow nanospheres, and the specific steps are: Step S1: Mix soluble iron salt, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine, dissolve in water and stir at room temperature to obtain reaction solution A, wherein the feed ratio of soluble iron salt, ascorbic acid, hexadecyltrimethylammonium bromide, hexamethylenetetramine and water is 0.01-0.08mmol: 0.001-0.04mmol: 0.01-0.05mmol: 0.01-0.08mmol: 5-20mL; Step S2: heating the reaction solution A obtained in step S1 to 80-120° C. and stirring under reflux for 1-12 hours to obtain reaction solution B; Step S3: The reaction solution B obtained in step S2 is precipitated by centrifugation with excess ethanol, washed multiple times, and then dispersed in water to obtain water-soluble amorphous iron oxide hollow nanospheres.

[0009] It is further defined that the soluble iron salt in step S1 is one or more of FeCl3, FeCl2, Fe(NO3)3, Fe(NO3)2, Fe2(SO4)3 or FeSO4.

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention prepares the target product, water-soluble amorphous iron oxide hollow nanospheres, by continuously stirring and refluxing a mixed aqueous solution of soluble iron salt, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine at 80-120° C. The synthesis process of the present invention is simple and easy to operate, and no high-temperature reactor is required, thereby reducing safety risks; 2. The iron oxide nanospheres prepared by the present invention are water-soluble, amorphous, degradable, and have a hollow structure. Their size is about 40-100 nm. Due to their nano size, large specific surface area and hollow structure, they have more active sites and can be further used to prepare targeted drug carriers or functional catalytic material carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The schematic diagram of the synthesis principle of the water-soluble amorphous iron oxide hollow nanospheres in the present invention.

[0012] Figure 2 This is the TEM image of the water-soluble amorphous iron oxide hollow nanospheres prepared in Example 1.

[0013] Figure 3 This is a high-resolution TEM image of the water-soluble amorphous iron oxide hollow nanospheres prepared in Example 1.

[0014] Figure 4 This is the XRD pattern of the water-soluble amorphous iron oxide hollow nanospheres prepared in Example 1.

[0015] Figure 5 This is the TEM image of the product obtained in Comparative Example 1.

[0016] Figure 6 This is the TEM image of the product obtained in Comparative Example 2.

[0017] Figure 7 This is the TEM image of the product obtained in Comparative Example 3. DETAILED DESCRIPTION

[0018] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Example 1

[0019] Step S1: Mix soluble iron salt FeCl3, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine, dissolve in water and stir at room temperature for 3 hours to obtain a reaction solution A, wherein the feed ratio of soluble iron salt FeCl3, ascorbic acid, hexadecyltrimethylammonium bromide, hexamethylenetetramine and water is 0.04mmol:0.01mmol:0.02mmol:0.02mmol:10mL; Step S2: heating the reaction solution A obtained in step S1 to 90° C. and stirring under reflux for 6 h to obtain reaction solution B; Step S3: The reaction solution B obtained in step S2 is precipitated by centrifugation with excess ethanol, washed multiple times, and then dispersed in water to obtain water-soluble amorphous iron oxide hollow nanospheres.

[0020] Figure 2 This is a TEM image of the water-soluble amorphous iron oxide hollow nanospheres prepared in this embodiment (characterized using a JEM-2100 transmission electron microscope from Japan Electronics). It can be seen from the figure that the size of the water-soluble amorphous iron oxide hollow nanospheres prepared in this embodiment is 50~80nm, it has a hollow structure and is evenly dispersed in water.

[0021] Figure 3 This is a high-resolution TEM image of the water-soluble amorphous iron oxide hollow nanospheres prepared in this example (characterized using a JEM-2100 transmission electron microscope of Japan Electronics). It can be seen from the image that the water-soluble amorphous iron oxide hollow nanospheres prepared in this example have no lattice and have a hollow structure.

[0022] Figure 4 This is the X-ray diffraction pattern of the water-soluble amorphous iron oxide hollow nanospheres prepared in this example (characterized by Rigaku Ultima IV X-ray diffractometer from Japan). It can be seen from the figure that the prepared water-soluble iron oxide hollow nanospheres are amorphous. Example 2

[0023] Step S1: Mix soluble iron salt Fe2(SO4)3, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine, dissolve in water and stir at room temperature for 3h to obtain a reaction solution A, wherein the feed ratio of soluble iron salt Fe2(SO4)3, ascorbic acid, hexadecyltrimethylammonium bromide, hexamethylenetetramine and water is 0.01mmol:0.001mmol:0.01mmol:0.01mmol:5mL; Step S2: heating the reaction solution A obtained in step S1 to 80° C. and stirring under reflux for 12 h to obtain reaction solution B; Step S3: The reaction solution B obtained in step S2 is precipitated by centrifugation with excess ethanol, washed multiple times, and then dispersed in water to obtain water-soluble amorphous iron oxide hollow nanospheres.

[0024] The sample was characterized by transmission electron microscopy (characterized by JEM-2100 transmission electron microscope, produced by Japan Electron). The size of the water-soluble amorphous iron oxide hollow nanospheres prepared in this example was about 40-70 nm. Example 3

[0025] Step S1: Mix soluble iron salt FeSO4, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine, dissolve in water and stir at room temperature for 3 hours to obtain a reaction solution A, wherein the feed ratio of soluble iron salt FeSO4, ascorbic acid, hexadecyltrimethylammonium bromide, hexamethylenetetramine and water is 0.08mmol:0.04mmol:0.05mmol:0.08mmol:20mL; Step S2: heating the reaction solution A obtained in step S1 to 120° C. and stirring under reflux for 1 h to obtain reaction solution B; Step S3: The reaction solution B obtained in step S2 is precipitated by centrifugation with excess ethanol, washed multiple times, and then dispersed in water to obtain water-soluble amorphous iron oxide hollow nanospheres.

[0026] The sample was characterized by transmission electron microscopy (characterized by JEM-2100 transmission electron microscope, produced by Japan Electron). The size of the water-soluble amorphous iron oxide hollow nanospheres prepared in this example was about 60-100 nm. Example 4

[0027] Step S1: Mix soluble iron salt Fe(NO3)3, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine, dissolve in water and stir at room temperature for 3h to obtain reaction solution A, wherein the feed ratio of soluble iron salt Fe(NO3)3, ascorbic acid, hexadecyltrimethylammonium bromide, hexamethylenetetramine and water is 0.02mmol:0.01mmol:0.02mmol:0.02mmol:10mL; Step S2: heating the reaction solution A obtained in step S1 to 100° C. and stirring under reflux for 4 h to obtain reaction solution B; Step S3: The reaction solution B obtained in step S2 is precipitated by centrifugation with excess ethanol, washed multiple times, and then dispersed in water to obtain water-soluble amorphous iron oxide hollow nanospheres.

[0028] The sample was characterized by transmission electron microscopy (using JEM-2100 transmission electron microscope, produced by Japan Electron). The size of the water-soluble amorphous iron oxide hollow nanospheres prepared in this example was about 40-60 nm.

[0029] Comparative Example 1 The other conditions are the same as those in Example 1, except that no ascorbic acid is added in step S1.

[0030] The samples were characterized by transmission electron microscopy (using JEM-2100 transmission electron microscope, manufactured by JEOL Ltd.). The samples prepared in this embodiment showed a cross-linked network structure and could not form water-soluble amorphous iron oxide hollow nanospheres.

[0031] Comparative Example 2 The other conditions are the same as those in Example 1, except that hexadecyltrimethylammonium bromide is not added in step S1.

[0032] The samples were characterized by transmission electron microscopy (using JEM-2100 transmission electron microscope, manufactured by JEOL Ltd.). The samples prepared in this embodiment showed a disordered small-sized nanoparticle structure and could not form water-soluble amorphous iron oxide hollow nanospheres.

[0033] Comparative Example 3 The other conditions are the same as those in Example 1, except that hexamethylenetetramine is not added in step S1.

[0034] The samples were characterized by transmission electron microscopy (using JEM-2100 transmission electron microscope, manufactured by JEOL Ltd.). The samples prepared in this embodiment showed large-sized non-uniform vesicle structures and could not form water-soluble amorphous iron oxide hollow nanospheres.

[0035] The basic principles, main features and advantages of the present invention are shown and described above. Without departing from the spirit and scope of the present invention, the present invention may also be subject to various changes and improvements, which all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing water-soluble amorphous iron oxide hollow nanospheres, characterized in that The specific steps are: Step S1: Mix soluble iron salt, ascorbic acid, hexadecyltrimethylammonium bromide and hexamethylenetetramine, dissolve in water and stir at room temperature to obtain reaction solution A, wherein the feed ratio of soluble iron salt, ascorbic acid, hexadecyltrimethylammonium bromide, hexamethylenetetramine and water is 0.01-0.08mmol: 0.001-0.04mmol: 0.01-0.05mmol: 0.01-0.08mmol: 5-20mL; Step S2: heating the reaction solution A obtained in step S1 to 80-120° C. and stirring under reflux for 1-12 hours to obtain reaction solution B; Step S3: The reaction solution B obtained in step S2 is precipitated by centrifugation with excess ethanol, washed multiple times, and then dispersed in water to obtain water-soluble amorphous iron oxide hollow nanospheres.

2. The method for preparing water-soluble amorphous iron oxide hollow nanospheres according to claim 1, characterized in that: The soluble iron salt in step S1 is one or more of FeCl3, FeCl2, Fe(NO3)3, Fe(NO3)2, Fe2(SO4)3 or FeSO4.

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